This invention relates to an improved variable resistance, weight training exercise machine and, in particular, to an improved variable resistance weight machine that is adapted for squat exercises.
Many persons use weight training to develop strength, to enhance their personal appearance, or to rehabilitate injuries. Typically, an exerciser will use either a weight exercise machine or various types of free weights, such as dumbbells, barbells, and weighted plates. Both types of weight training have advantages and disadvantages.
Free weights are generally more inexpensive and more versatile than weight exercise machines. One set of free weights can be used to work many different muscle groups. Free weights also offer an improved range of motion over exercise machines, which are restricted to one plane of movement.
The primary disadvantage of free weights is safety. Because free weights are not restricted to a particular range of motion, as in weight machines, various mishaps can occur. An exerciser can drop a weight on himself, a bar can become unbalanced while adding or removing weights, or an exerciser could be trapped underneath a weighted bar. Because of those safety risks, most exercisers who use free weights have to work out in pairs or specialized facilities to protect themselves. That also limits the exerciser to times and places where they can work out.
Because of the disadvantages of free weights, exercise machines have become more common, especially in commercial facilities where liability concerns over free weights are present. Weight exercise machines avoid the risk of certain injuries because the weights are usually restricted to a certain range of motion. Thus, if properly loaded on the machine, weights cannot fall on an exerciser, nor can the exerciser be pinned under a bar loaded with weights. Exercise machines also tend to be more stable. Weights typically can be added or removed from machines without risking an imbalance that could cause a weight to fall on and injure an exerciser.
The prior art has countless disclosures relating to exercise machines designed for improving the muscle characteristics of different muscle groups. Such prior art machines include multistation machines, i.e., machines that allow an exerciser to perform more than one type of exercise, as well as single station machines that are specially adapted to a particular exercise. For example, U.S. Pat. No. 5,184,991, discloses a multistation exercise machine for performing various exercises designed to work different muscle groups. That multistation machine uses a series of cables, pulleys, and levers that transmit the resistance and load of weights while restricting the weights to a particular range of motion. U.S. Pat. No. 5,135,449 discloses a single station machine designed to provide rowing exercise. That machine uses a pair of levers to provide the resistance to an exerciser.
Multistation exercise machines have an advantage in that they are capable of providing a variety of exercises in a relatively compact machine. Multistation machines also can be manufactured and sold more economically, thus making them more suitable for the home market than are single station machines. An example of a multistation machine having such advantages is disclosed in applicant""s copending U.S. application, Ser. No. 09/346,476, filed on Jul. 1, 1999, the disclosure of which is hereby incorporated by reference. It allows an exerciser to perform a wide variety of exercises, such as lat pull downs, military presses, chest presses, triceps extensions, seated dips, biceps curls, low rows, lying leg presses, squats, dead lifts, abdominal crunches, leg extensions, seated leg curls, and lat pull-overs, and it is easily and economically fabricated.
Single station machines, however, are generally preferred in the commercial market where there are many exercisers sharing the same equipment. Gyms, health clubs, and professional training facilities prefer to have an array of single station machines, each specially adapted for a particular exercise. Exercisers do not have to spend time making adjustments that often are necessary in a multistation machine in order to adapt it to a different exercise.
Whether single station or multistation, however, many exercise machines are relatively difficult and costly to build. Many designs require a relatively large number of specialized components such as levers, pulleys, cables, and the like. Such specialized components increase the complexity of the design and the time to assemble the machines. The cost to build and repair such machines also is relatively high when compared with those that do not require specialized components.
In addition, free weights and most exercise machines on the market today are designed to provide a constant resistance and load over the entire range of motion in an exercise. Preferably, the resistance and, thereby, the force needed to move a given weight could be varied over the range of motion needed to perform an exercise such that an exerciser encounters the greatest resistance when his muscoskeletal system is in the best position to bear the greatest resistance. Likewise, the load provided by weights preferably would vary over the range of motion. Variable resistance and load also can allow for more efficient weight training by causing muscle groups to work hardest at a specified range of motion or by focusing greater resistance and load on different muscle groups. They can help prevent injury as well by allowing an exerciser to exert less force at vulnerable points in a range of motion during an exercise.
For example, one of the most popular exercises in weight training is the squat. In a squat, an exerciser lifts a weight from a squatting position to an upright position. During the initial range of motion, as the exerciser is rising from the lowest, squatting position, he is at the greatest risk of back injury. It would be preferable to allow the exerciser to initially lift the weight with less force at this vulnerable position. Then, as the exerciser continues through the range of motion to a more upright posture, where the risk of injury is lessened and the muscoskeletal system is capable of bearing greater weight, the force necessary to move the weight preferably would increase.
Through the initial range of motion in a squat, the gluteus maximus and hamstrings of an exerciser provide the majority of the lift needed to overcome the resistance of the weights. As the exerciser becomes more upright, however, the quadriceps provide most of the lift. Many squat exercise machines, however, are unable to vary the resistance such that those separate muscle groups are isolated and preferentially worked during a squat.
At the same time, however, many exercisers enjoy competition. Free weights typically are used in competition, and thus, it is important that training machines can provide more or less uniform resistance and load matching the nominal weight of standard weights. That is, a variable resistance exercise machine should be designed that an exerciser can lift approximately the same weight, through the same resistance profile on a training machine as he would be able to do with free weights in competition.
An object of the subject invention, therefore, is to provide a squat exercise that provides a reduced risk of injury to an exerciser during weight training.
Another object is to provide a squat machine in which the weights are restricted to a defined range of motion such that an exerciser may safely exercise without the assistance of others.
It also is an object of the invention to provide a variable resistance squat exercise machine.
Another object of the subject invention is to provide a squat exercise machine that has substantially constant resistance so as to replicate more closely the resistance profile and nominal resistance of free weights.
Yet another object is to provide a variable resistance squat exercise machine that is able to isolate and focus resistance on the major muscle groups required to perform a squat.
Yet another object of the subject invention is to provide a squat exercise machine that is more easily manufactured and assembled.
It is a further object of this invention to provide a squat exercise machine wherein some or all of the above-mentioned advantages are realized.
Those and other objects and advantages of the invention will be apparent to those skilled in the art upon reading the following detailed description and upon reference to the drawings.
The subject invention provides for an exercise machine for performing squat exercises. The exercise machine comprises a support frame with a shaft horizontally mounted on the frame for rotation about its longitudinal axis. There is at least one weight arm connected to the shaft. The weight arm is adapted to carry a weight at a point distant from the connection between the weight arm and the rotating shaft. Thus, the weight arm provides resistance and load as the shaft rotates. (Although they are technically distinct concepts, resistance and load are commonly, and at times may be referred to herein in a collective sense as simply resistance.)
The novel squat machines also comprise a work arm that is connected to the shaft such that actuation of the work arm causes the shaft to rotate. A yoke is connected to the work arm. The yoke is adapted to accommodate the shoulders of an exerciser such that the exerciser is able to provide upward force on the work arm in opposition to the resistance of the weight arm by performing a squat exercise. When the exerciser performs the squat, the work arm causes the shaft to rotate and the weight arm to travel along an arcuate path. Thus, the resistance to rotation provided by the weight arm varies as the weight arm travels along its arcuate path.
It will be appreciated, therefore, that because the motion of the weight arm follows an arcuate path the resistance provided during a squat exercise varies. Moreover, the arcuate path may be predetermined such that there is relatively less weight resistance during the vulnerable, initial range of motion in a squat. Because the weight arm""s range of motion is restricted, the machine also provides increased safety and allows an exerciser to work out alone.
Preferably, the work arm carries one or more second weights at a point distant from the connection between the work arm and the rotating shaft. Such weights provide resistance to upward movement of the work arm, and like the weights carried on the weight arms, the second weights also travel along an arcuate path. Thus, the resistance to upward movement of the work arm varies during a squat exercise.
More particularly, as an exerciser assumes an initial, squatting position, the weights on the weight arm preferably are carried at a position of between 180xc2x0 and 270xc2x0. Thus, as the exerciser rises from the squatting position, the work arm causes the shaft to rotate in a clockwise direction, which in turn causes the weight arm and its associated weights to travel clockwise along an arcuate path.
The resistance provided by those weights, therefore, will increase as they travel along their arcuate paths. Preferably, the weights are approaching horizontal as the exerciser is approaching his full upright position and finishes in a substantially horizontal position. Thus, the weights on the weight arm will provide less resistance when the exerciser is in the vulnerable, squatting position. They will provide the greatest resistance near the finish position at a point where the quadriceps are providing the greatest lift and the exerciser is at less risk of injury.
As for the second weights carried on the work arm, preferably they are positioned between 270xc2x0 and 0xc2x0 when the exerciser is in the initial, squatting position. As the exerciser lifts the work arm, the second weights travel along an arcuate path to a substantially vertical finishing position. Thus, the resistance provided by the second weights decreases as the exerciser progresses toward the finishing position. Because the exerciser is a greatest risk of injury in his squatting position, typically the work arm will not carry as much weight and provide as much resistance as the weights on the weight arms.
It will be appreciated, however, that by selectively varying the amount of weight carried on the weight arms and on the work arms, the novel exercise machines may focus resistance either through the initial range of motion in a squat exercise, where most of the lift is provided by the gluteus maximus and hamstrings, or through the latter range of motion, where most of the lift is provided by the quadriceps.
The first and second weights also may be selected such that the increasing resistance of the weights on the weight arms is substantially offset by the decreasing resistance provided by the work arm weights. Thus, the overall resistance provided by the machine may be made substantially constant over the entire range of motion and made to match the nominal resistance of free weights.
These and other features of the invention will be more readily understood in view of the following detailed description and drawings.